Small volume cell

ABSTRACT

A small internal volume cell having fluid entry, and exit ports wherein bubble traps are present in a bifurcated fluid pathway continuous with the fluid exit port. There further being present input and output apertures, for entering and exiting electromagnetic radiation, positioned to allow causing a beam of electromagnetic radiation to impinge on a sample substrate at a location thereon at which, during use, fluid contacts; as well as methodology of its use.

CROSS-REFERENCE TO OTHER APPLICATIONS

This Application Claims Benefit of Provisional Application Ser. No.60/961,996 Filed Jul. 26, 2007.

TECHNICAL FIELD

The present invention relates to cells for containing fluid to beinvestigated by electromagnetic radiation, and more particularly to asmall internal volume cell comprising fluid entry and exit portsincluding bubble traps, and input and output apertures for entering andexiting electromagnetic radiation, as well as methodology of use.

BACKGROUND

It is known to apply cells for receiving fluids and investigating samplein said fluid with electromagnetic radiation. For instance, a Patent toWoollam et al., U.S. Pat. No. 6,937,341 that enables simultaneousinvestigation of a sample in a fluid with two beams of electromagneticradiation.

A computer search was conducted to identify Patents which discuss smallfluid cells and ellipsometry, and none were found. However, a Patent toBattiston et al., U.S. Pat. No. 7,389,679 was identified as it doesdisclose cell for containing small amounts of fluid. The design of thecell, however, is very different from that of the present invention. Inparticular fluid entry ports are at a lower extent of the 679 systemwhich means bubbles rise through entered fluid. As disclosed herein, inthe Detailed Description Section and Drawings, the present inventionsystem provides for a very different fluid entry configuration.

Need remains for additional small cells for use in investigating fluidsamples with electromagnetic radiation, and in particular small cellswhich provide means for reducing the effect of bubbles caused by entryof the fluid into said small cell.

DISCLOSURE OF THE INVENTION

The present invention is a small internal volume cell comprising asample substrate at a lower extent thereof, and laterally separatedfluid entry and exit ports at an upper extent thereof, as viewed inelevation. The small internal volume cell further comprises input andoutput apertures for entering and exiting, respectively, a beam ofelectromagnetic radiation, which are affixed to laterally separatedsides of the small volume cell, to allow entry and exit, respectively,of a beam of electromagnetic radiation known angles-of-incidence andreflection, as viewed in frontal elevation. Said small internal volumecell is characterized by the presence of at least one bubbleaccumulating trap region in a fluid exit pathway to said exit port,which bubble trap(s) serve to accumulate bubbles produced during theentry and exit of fluid, into and from, said small internal volume cell.

In use, fluid is caused to enter said fluid input port and is directedto be contact said sample substrate, then said fluid exits via said exitport. During use, simultaneously, a beam of electromagnetic radiation iscaused to enter said input aperture, reflect from said sample substratenear the location at which said fluid is caused to contact said samplesubstrate, and exits said output aperture.

The input port is continuous with a single fluid entry pathway that endsat a point above the sample substrate, near a location thereon at whichfluid entered to said input port, contacts during use. And, said outputport is continuous with a fluid exit pathway which bifurcates into twolaterally opposed pathways that serve to receive fluid which ispresented to said sample substrate, and flows therefrom in laterallyopposed directions.

The preferred embodiment of the cell has an internal volume which is onthe order of one-half (0.5) milliliter or less, and can further comprisetemperature control means for controlling the temperature of said samplesubstrate.

The small internal volume cell can be further characterized by a reduceddiameter aperture region between the input aperture and the samplesubstrate, and the sample substrate can be selected to be of acomposition so as to selectively secure thereto a component in a fluidpresented thereto, to the exclusion of other components. An example isto provide a sample substrate which is composed of gold on glass, andprovide a fluid which includes biotin. The effective sample which theelectromagnetic beam impinges on becomes biotin attached to the gold.Another example is that a substrate to which is applied “dirt” can beaffected by a fluid which contains “soap”. The electromagnetic beam canmonitor the removal of the dirt as the soap flows thereby. Stillanother, very basic, example is to provide an effectively inert samplesubstrate and flow a fluid for which the optical constants are to bedetermined. In such examples, it is noted that the fluid is typically,but not necessarily, a liquid. That is, it can be, for instance, a gas.The present invention then includes providing a sample substrate whichhas a composition appropriate to the task, said composition being, forinstance, characterized as a selected from the group:

-   -   chemically inert;    -   chemically reactive with at least one component in a fluid.    -   chemically reactive with one component in a fluid and not other        components.

A method of investigating a sample present in a fluid comprises thesteps of:

-   -   a) providing a cell as just described above;    -   b) causing sample containing fluid to be entered into said cell        internal volume, with any bubbles produced accumulating in said        bubble traps;    -   c) causing a beam of electromagnetic radiation to enter said        input aperture, proceed through said fluid, reflect from said        sample substrate and exit said output aperture;    -   d) causing said exiting beam of electromagnetic radiation to        enter a data detector.

Said method can further comprise:

-   -   e) performing at least one selection from the group consisting        of:        -   storing at least some data provided by said data detector in            machine readable media;        -   analyzing at least some of the data provided by said data            detector and storing at least some of the results of said            analysis in machine readable media;        -   displaying at least some data provided by said data detector            by electronic and/or non-electronic means;        -   analyzing at least some of the data provided by said data            detector and displaying at least some of the results of said            analysis by electronic and/or non-electronic means;        -   causing at least some data provided by said data detector to            produce a signal which is applied to provide a concrete and            tangible result;        -   analyzing at least some of the data provided by said data            detector and causing at least some thereof to produce a            signal which is applied to provide a concrete and tangible            result.

Said method can further comprises providing a polarized electromagneticbeam in step c.

The present invention is also an ellipsometer system that comprises:

-   -   a source of a beam of electromagnetism;    -   a polarizer;        -   a small internal volume cell comprising a sample substrate            at a lower extent thereof, said small internal volume cell            further comprising laterally separated fluid entry and exit            ports at an upper extent thereof and input and output            apertures for entering and exiting a beam of electromagnetic            radiation affixed to laterally separated sides thereof, to            allow entry and exit at known angles-of-incidence and            reflection, as viewed in frontal elevation;        -   said small internal volume cell being characterized by the            presence of at least one bubble accumulating trap region in            a fluid exit pathway to said exit port for accumulating            bubbles produced during the entry and exit of fluid from            said small volume cell;        -   said small internal volume cell being further characterized            in that said input port is continuous with a single fluid            entry pathway that ends at a point above the sample            substrate, at a location thereon near which fluid entered to            said input port, contacts during use; and said output port            is continuous with a fluid exit pathway which bifurcates            into two laterally opposed pathways that serve to receive            fluid which contacts said sample substrate, and flows            therefrom in laterally opposed directions;        -   such that in use, while fluid is caused to enter said input            port and contact said sample substrate, then exit via said            exit port, a beam of electromagnetic radiation is caused to            enter said input aperture, reflect from said sample            substrate near the location at which said fluid contacts            said sample substrate, and exit said output aperture;    -   a polarizer; and    -   a detector.        Again, the small internal volume of small internal volume cell        can be about one-half (0.5) milliliter or less; there can be        present a temperature control means for controlling the        temperature of said substrate for supporting a sample of said        internal volume of small internal volume cell; the internal        volume of small internal volume cell can be further        characterized by a reduced diameter aperture region between the        input aperture and the sample substrate thereof; there can be at        least one compensator between said polarizer and analyzer; and        said source of a beam of electromagnetism can be mono-chromatic        or spectroscopic.

The invention will be better understood by reference to the DetailedDescription Section of this Specification, in combination with theDrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a representation of the present small internal volume cell(C), in frontal elevation.

FIG. 2 shows a general elemental configuration of an ellipsometer system(E) which can be applied in combination with the small internal volumecell (C).

DETAILED DESCRIPTION

Turning now to the Drawings, there in shown in FIG. 1 a representationof the Present Invention Small Internal Volume Cell (C). Shown are aneffective Sample Substrate (STG) at a lower extent thereof. Said SmallInternal Volume Cell (C) further comprises Fluid (L) Entry (IN) and Exit(OUT) Ports and Bubble Traps (BT) in pathways to said Exit (OUT) Port,and Input (IA) and Output (OA) Apertures for entering (EMI) and exiting(EMO) a Beam of Electromagnetic Radiation. Said Entry (IN) and Exit(OUT) Ports are shown to be laterally separated from one another atopsaid Small Internal Volume Cell (C), and said Input (IA) and Output (OA)Apertures for entering (EMI) and exiting (EMO) a Beam of ElectromagneticRadiation are affixed to laterally separated sides of said SmallInternal Volume Cell (C) to allow entry at a known obliqueangle-of-incidence, (eg. θ=70 degrees), as viewed in the FIG. 1 frontalelevation. Said Small Internal Volume Cell (C) is distinguished by thepresence of said Bubble Accumulating Trap (BT) regions in at least onepathway to said Exit (OUT) port, for accumulating bubbles producedduring the entry and exit of fluid from said Small Internal Volume Cell(C). Note that FIG. 1 shows that the preferred embodiment provides twopathways for fluid to follow to the Exit (OUT) Port. FIG. 1 shows thatin use, fluid (L) which is entered to Input (IN) Port exits onto saidSample Substrate (STG) via a Fluid Exit (LE) opening at the end of aFluid (L) input pathway, at a location thereupon from which a Beam ofElectromagnetic Radiation (EMI) is caused to reflect.

It is further noted that associated with the Input Aperture (IA) is aReduced Diameter Aperture Region (IAP). This serves to diminishinteraction of the entered Beam of Electromagnetic Radiation (EMI) withsides of the pathway through which it proceeds to the Sample Substrate(STG). That is, reflections from the sides of the effective bore betweenthe Bubble Traps (BT) and the Sample Substrate (STG) are greatly reducedover what they would be if the Reduced Diameter Aperture Region (IAP)were not present.

It is to be understood that the Sample Substrate (STG) can be of variouscompositions to interact with components deposited thereonto from theFluid (L). For instance, the Sample Substrate (STG) can be, but doeshave to be, comprised of a material to which some component in a Fluid(L) attaches, to the exclusion of other components. That Is, thecomposition of the Sample Substrate (STG) can be selected so that itsecure thereto a component in a fluid, to the exclusion of othercomponents. While the Sample Substrate (STG) can alone comprise a Sample(SM), when a Component from a-fluid is affixed thereto, the combinationof the fluid component in combination with the Sample Substrate (STG),form a Sample (SAM).

Note the presence of “O” rings, (shown generally as circles), which, inthe case of the Input (IA) and Output (OA) Apertures for entering (EMI)and exiting (EMO) a Beam of Electromagnetic Radiation, serve to reducestress induced effects that can affect Electromagnetic beamcharacteristics.

It is disclosed that the Small Internal Volume Cell (C) can be modifiedto provide a single Port, such as Input Port (IA), which serves to bothenter (EMI) and exit (EMO) a Beam of Electromagnetic Radiation. Themodification involves placing a mirror where the Output Aperture (OA) isshown in FIG. 1.

FIG. 2 is included to show a general elemental configuration of anEllipsometer System (E) which can be applied in combination with thesmall internal volume cell (C). Note there is present a Source (LS) of aBeam of electromagnetic radiation which is directed to pass through aPolarizer (P) and appear as (EMI) which enters the Small Internal VolumeCell (C), interacts with a fluid sample therein, exits and passesthrough an Analyzer (A) and enters a Detector (DET). Note alsoidentified are optional Compensators (C1) (C2), which can be stationaryor rotated in use, and general representation of “additional elements”(AC1) (AC2) which might include, for instance, focusing elements. In usethe Polarizer (P) imposes a state of polarization on Beam (EMI), whichis changed by interaction with the fluid sample in the Small InternalVolume Cell (C), then monitored by the Analyzer and the Detector (DET).

It is noted that the terminology “Sample” as used herein can refer to afluid per se. which contacts the Sample Substrate (STG), or componentsin said fluid which deposit on, or attach to, the Sample Substrate(STG).

Having hereby disclosed the subject matter of the present invention, itshould be obvious that many modifications, substitutions, and variationsof the present invention are possible in view of the teachings. It istherefore to be understood that the invention may be practiced otherthan as specifically described, and should be limited in its breadth andscope only by the Claims.

1. A small internal volume cell comprising a sample substrate at a lowerextent thereof, said small internal volume cell further comprisinglaterally separated fluid entry and exit ports at an upper extentthereof and input and output apertures for entering and exiting a beamof electromagnetic radiation affixed to laterally separated sidesthereof, to allow entry and exit at known angles-of-incidence andreflection, as viewed in frontal elevation; said small internal volumecell being characterized by the presence of at least one bubbleaccumulating trap region in a fluid exit pathway to said exit port foraccumulating bubbles produced during the entry and exit of fluid fromsaid small volume cell; such that in use, while fluid is caused to entersaid input port and contact said sample substrate, then exit via saidexit port, a beam of electromagnetic radiation is caused to enter saidinput aperture, reflect from said sample substrate at or near thelocation at which said fluid is caused to contact said sample substrate,and exit said output aperture.
 2. A small internal volume cell as inclaim 1 wherein the internal volume thereof is about one-half (0.5)milliliter or less.
 3. A small internal volume cell as in claim 1 whichfurther comprises a temperature control means for controlling thetemperature of said sample substrate.
 4. A small internal volume cell asin claim 1, in which said input port is continuous with a single fluidentry pathway that ends at a point above the sample substrate, at alocation thereon near which fluid entered to said input port contactsduring use; and said output port is continuous with a fluid exit pathwaywhich bifurcates into two laterally opposed pathways that serve toreceive fluid which contacts said sample substrate, and flows therefromin laterally opposed directions.
 5. A small internal volume cell as inclaim 1, which is further characterized by a reduced diameter apertureregion between the input aperture and the sample substrate.
 6. A smallinternal volume cell as in claim 1, which is further characterized by asample substrate which is selected to be of a composition so as toselectively secure thereto a component in a fluid, to the exclusion ofother components.
 7. A small internal volume cell as in claim 1, whereinthe fluid is a liquid.
 8. A method of investigating a fluid or samplepresent in a fluid comprising the steps of: a) providing a smallinternal volume cell comprising an internal volume of about 0.5 ml orless, said small internal volume cell further comprising a samplesubstrate at a lower extent thereof, said small internal volume cellfurther comprising laterally separated fluid entry and exit ports at anupper extent thereof and input and output apertures for entering andexiting a beam of electromagnetic radiation affixed to laterallyseparated sides thereof, to allow entry and exit at knownangles-of-incidence and reflection, as viewed in frontal elevation; saidsmall internal volume cell being characterized by the presence of atleast one bubble accumulating trap region in a fluid exit pathway tosaid exit port for accumulating bubbles produced during the entry andexit of fluid from said small volume cell; such that in use, while fluidis caused to enter said input port contacts said sample substrate, thenexit via said exit port, a beam of electromagnetic radiation is causedto enter said input-aperture, reflect from said sample substrate at ornear the location at which said fluid is caused to contact said samplesubstrate, and exit said output aperture; b) causing a fluid or samplecontaining fluid to be entered into said small internal volume cellinternal volume, with bubbles produced accumulating in said bubbletraps; c) causing a beam of electromagnetic radiation to enter saidinput aperture, proceed through said fluid, reflect from said samplesubstrate and exit said output aperture; d) causing said exiting beam ofelectromagnetic radiation to enter a data detector.
 9. A method as inclaim 8 in which the sample substrate is selected from the group:chemically inert; chemically reactive with at least one component in afluid; chemically reactive with one component in a fluid and not othercomponents.
 10. A method as in claim 7 which further comprises: e)performing at least one selection from the group consisting of: storingat least some data provided by said data detector in machine readablemedia; analyzing at least some of the data provided by said datadetector and storing at least some of the results of said analysis inmachine readable media; displaying at least some data provided by saiddata detector by electronic and/or non-electronic means; analyzing atleast some of the data provided by said data detector and displaying atleast some of the results of said analysis by electronic and/ornon-electronic means; causing at least some data provided by said datadetector to produce a signal which is applied to provide a concrete andtangible result; analyzing at least some of the data provided by saiddata detector and causing at least some thereof to produce a signalwhich is applied to provide a concrete and tangible result.
 11. A methodas in claim 8 which further comprises providing a polarizedelectromagnetic beam in step c.